Prefabricated bridge deck unit



1967 A. J. OUDHEUSDEN, JR. ETAL 3,302,361

PREFABRICATED BRIDGE DECK UNIT Filed OCT.- 16, 1964 2 Sheets-Sheet 1 Fig.

INVENTORS A/berf J. Oudheusden Jn Lawrence 6. Adams Feb. 7, 1967 A. J. OUDHEUSDEN, JR. ETAL 3,30

PREFABRICATED BRIDGE DECK UNIT File d Oct. 16, 1964 2 Sheets-Sheet 2 h I I! INVENTORS A/berf J. Oudheusaen Jr.

:5 S Lawrence 6. Adams United States Patent M 3,302,361 PREFABRICATED BRIDGE DECK UNIT Albert J. Oudheusden, Jr., and Lawrence G. Adams, Bethlehem, Pa., assignors, by mesne assignments, to Bethlehem Steel Corporation, a corporation of Delaware Filed Oct. 16, 1964, Ser. No. 404,473 4 Claims. (Cl. 52618) This invention relates to a prefabricated structural unit and more particularly to a welded metal structural unit for constructing bridges.

Most short span steel bridges being built today use either a truss or girder type of construction and usually use a poured concrete deck as the roadway. Both the truss and girder bridges require fairly heavy structural members in order to carry the dead loads imposed on the bridge by the heavy concrete deck. The truss and girder bridges also often contain a number of members which are either redundant or are stressed far below their allowable limits. Furthermore, truss and girder bridges are assembled primarily in the field resulting in long delays in opening the spans to traffic.

It is therefore an object of our invention to provide a strong but lightweight structural unit suitable for building bridges in which each member of the structural unit is worked close to the allowable limit of its load bearing capacity.

It is a. further object of our invention to provide a prefabricated structural unit which will permit a bridge superstructure to be erected in less than one day.

It is a still further object of our invention to provide a structural unit in a bridge in which all the members are designed and positioned to contribute to the overall live load bearing capacity of the bridge.

It is a still further object of our invention to provide a structural unit which can be fabricated using modern high speed automatic welding techniques.

With these general objects in view and such others as may hereinafter appear, the invention resides in a prefabricated structural unit comprising a pair of longitudinal stringers, a compression deck member and a plurality of transverse members welded together to form an integral unit.

In the drawings illustrating the preferred embodiment of the invention:

FIGURE 1 is an isometric view partially in section of one of the prefabricated structural units embodying our invention.

FIGURE 2 is a sectional view taken at approximately midspan of a bridge constructed using four of the prefabricated structural units embodying our invention.

FIGURE 3 is a fragmentary sectional view showing the fabrication of the compression deck member and the transverse members.

Referring to FIGURE 1, the prefabricated structural unit 1 comprises a pair of parallel longitudinal stringers 2, a continuous deck member 3 welded to the top edges of the longitudinal stringers 2 and a plurality of transverse members 4 welded to the underside of the continuous deck member 3 and extending continuously through slots 5 formed in the longitulinal stringers 2 and welded thereto.

The longitudinal stringers 2 are fabricated from a pair of metal plates welded together at right angles to each other to form an inverted T. Plate 6 serves as a bottom tension flange member and plate 7 serves as a web member. Each of these plates is of a length substantially equal to the free span of the bridge to be constructed using the prefabricated structural units 1. The top edge of plate web member 7 is welded to the underside of deck member 3.

3 302,361 Patented Feb. 7, 1967 The continuous deck 3 is comprised of a rectangular metal plate 8 welded to the top surfaces of a rectangular corrugated metal sheet 9 to form a compression member which is rigid in two directions. Rectangular metal plate 8 and rectangular corrugated metal sheet 9 are preferably of a length substantially equal to the free span of the bridge to be built using the prefabricated structural units 1. Because of the cooperation among the various members in the prefabricated structural unit 1, metal plate 8 and corrugated sheet 9 can be formed from relatively thin material, thus providing a lightweight deck member 3.

The trapezoidal shape of corrugation was found to be the most desirable considering both the fabrication and strength viewpoints. A non'symmetrical cross section having the valleys wider than the crests of the corrugations is used to provide a lower neutral axis in the deck member 3 than would be the case if a symmetrical corrugated sheet were used, with a minimum amount of metal.

In fabricating the prefabricated structural unit 1, the corrugations of sheet 9 are arranged parallel to the longitudinal stringers 2 as shown in FIGURE 1.

Transverse members 4 are shown in FIGURE 1 as rectangular metal bars extending the full width of the prefabricated structural unit 1, at right angles to longitudinal stringers 2. Structural shapes other than rectangular bars such as T sections, channels or bulb channels, could also be used for transverse members 4. The transverse members extend through vertical slots 5 formed in the plate web members 7 of the longitudinal stringers 2. The ends of transverse members 4 are cantilevered from the stringers 2 and are punched with holes 10 to facilitate the bolting together of several of the prefabricated structural units 1 into a bridge as shown in FIG- URE 2. Vertical slots 5 have enlargements 11 at the ends to reduce stress concentrations resulting from loads being applied to deck member 3. The transverse members 4 are fastened to the underside of deck member 3 to provide lateral support for deck member 3 by welding the lower face of the valleys in corrugated sheet 9 to alternate sides of the top edges of transverse members 4.

FIGURE 2 illustrates four of the prefabricated structural units 1 arranged in side-by-side relationship on abutments 12 to form a bridge. One of the prefabricated structural units 1 has been raised slightly on the abutment by members 13 to provide a walkway at one side of the bridge. Adjacent units 1 are joined by using splice plates 14- and bolts inserted in holes 10 of the transverse members 4. These joints need be designed only for simple shear stresses. The longitudinal stringers are further tied together using horizontal angle struts 15 bolted between the lower portions of web members 7 and diagonal struts 17 at the center and ends. This bolting plus the welding together of the abutting edges of plates 8 constitutes the only field assembly work required in assembling the bridge.

While in some cases the rectangular metal plate 8 of deck member 3 may serve as the wearing surface for traffic, it is preferable to place a thin layer of bituminous concrete 16 or the like to the top surface of plate 8.

Eight structural units 1 for a bridge 32 feet wide having two spans of 56 feet each, were placed into position in approximately four hours. Each of the units 1 was 56 feet long and 8 feet wide. The deck member 3 consisted of a 7 flat steel plate 8 welded to the top surface of a A thick corrugated steel sheet 9. Longitudinal stringers 2 were fabricated using a 36" x steel plate for web member 7 and a 1" X 11" steel plate for tension flange member 6. 1" x 9" rectangular steel plates served as transverse members 4.

As many possible embodiments may be made of the invention without departing from the scope thereof, it is to be understood that all matter set forth herein or shown in the accompanying drawing is to be interpreted as illustrative and not in a limiting sense.

We claim:

1. A prefabricated structural unit comprising:

(a) a pair of parallel longitudinal stringers each con sisting of a bottom tension flange member and a plate web member having a plurality of vertical slots having enlarged ends formed therein at spaced inter vals along the length thereof,

(b) a continuous deck compression member welded to the top edges of the plate web members, the continuous deck compression member comprising a corrugated metal sheet having a plurality of crests and valleys formed therein, the valleys being wider than the crests and extending in a direction parallel to the longitudinal stringers, and a metal plate welded to the crests of the corrugated metal sheet, and

(c) a plurality of transverse members extending continuously through and cantilevered from the slots formed in the plate web members, and welded solely to the plate web member and to the valleys of the corrugated metal sheet.

2. A prefabricated structural unit comprising:

(a) a pair of parallel longitudinal stringers each consisting of a bottom tension flange member and a plate Web member having a plurality of vertical slots having enlarged ends formed therein at spaced intervals along the length thereof,

(b) a continuous deck compression member welded to the top edges of the plate web members, the continuous deck compression member comprising a series of spaced longitudinal upwardly facing cells of trapezoidal cross section welded to the underside of a flat plate member,

(c) a plurality of transverse members extending continuously through and cantilevered from the slots formed in the plate web members, and welded solely to the plate web members and to the bottoms of 4- the longitudinal cells of the compression member.

3. A fabricated structural unit comprising:

(a) at least one longitudinal stringer consisting of a bottom tension flange member and a plate Web member having a plurality of vertical slots having enlarged ends formed therein at spaced intervals along the length thereof,

(b) a continuous deck compression member welded to the top edge of the plate web member of each stringer, the continuous deck compression member comprising a series of spaced longitudinal upwardly facing cells of trapezoidal cross section Welded to the underside of a flat plate member,

(0) a plurality of transverse members extending continuously through and cantilevered from the slots formed in the plate Web member, and welded solely to the plate web member of each stringer and to the bottoms of the longitudinal cells of the compression member.

4. A fabricated structural unit comprising:

(a) a plurality of longitudinal stringers each consisting of a bottom tension flange member and a plate web member having a plurality of vertical slots having enlarged ends formed therein at spaced intervals along the length thereof,

(b) a continuous deck compression member welded to the top edges of the plate Web members, the continuous deck compression member comprising a series of spaced longitudinal upwardly facing cells of trapezoidal cross section welded to the underside of a flat plate member,

(c) a plurality of transverse members extending continuously through and cantilevered from the slots formed in the plate web members, and welded solely to the plate Web members and to the bottoms of the longitudinal cells of the compression member.

No references cited.

RICHARD W. COOKE, JR., Primary Examiner. 

1. A PREFABRICATED STRUCTURAL UNIT COMPRISING: (A) A PAIR OF PARALLEL LONGITUDINAL STRINGERS EACH CONSISTING OF A BOTTOM TENSION FLANGE MEMBER AND A PLATE WEB MEMBER HAVING A PLURALITY OF VERTICAL SLOTS HAVING ENLARGED ENDS FORMED THEREIN AT SPACED INTERVALS ALONG THE LENGTH THEREOF, (B) A CONTINUOUS DECK COMPRESSION MEMBER WELDED TO THE TOP EDGES OF THE PLATE WEB MEMBERS, THE CONTINUOUS DECK COMPRESSION MEMBER COMPRISING A CORRUGATED METAL SHEET HAVING A PLURALITY OF CRESTS AND VALLEYS FORMED THEREIN, THE VALLEYS BEING WIDER THAN THE CRESTS AND EXTENDING IN A DIRECTION PARALLEL TO THE LONGITUDINAL STRINGERS, AND A METAL PLATE WELDED TO THE CRESTS OF THE CORRUGATED METAL SHEET, AND (C) A PLURALITY OF TRANSVERSE MEMBERS EXTENDING CONTINUOUSLY THROUGH AND CANTILEVERED FROM THE SLOTS FORMED IN THE PLATE WEB MEMBERS, AND WELDED SOLELY TO THE PLATE WEB MEMBER AND TO THE VALLEYS OF THE CORRUGATED METAL SHEET. 